feat(patterns): add generate_frontmatter for PKM/Obsidian users

[OdinKral]

Summary

Adds generate_frontmatter — a pattern that produces clean, paste-ready YAML frontmatter from any text input.

Designed for PKM workflows (Obsidian, Logseq, or any markdown notes vault), but useful for anyone who wants structured metadata quickly.

Output fields

Field	Description
title	Exact or inferred title
aliases	1–3 alternative names to search by
tags	3–8 specific lowercase tags, supporting hierarchy (philosophy/stoicism)
type	Document type: article, chapter, transcript, meeting-notes, essay, reference, idea, book
author	Extracted or omitted
source	URL or citation if available
date	Document date or omitted
summary	One sentence (15–25 words) capturing the core content
status	Starts as unprocessed

Usage

cat article.md     | fabric -p generate_frontmatter
pbpaste            | fabric -p generate_frontmatter
yt URL --transcript | fabric -p generate_frontmatter

Output is only the YAML block — paste directly at the top of a note.

Design notes

• Tags use lowercase + hyphens; hierarchical tags use slash notation
• Fields that can't be inferred are omitted rather than guessed
• Summary is always a complete sentence, not a fragment
• Status defaults to unprocessed as the entry point for a processing workflow

Closes #1235.

🤖 Generated with Claude Code